PSYCH 1101 CHAPTER 6 SENSATION AND PERCEPTION SENSING THE WORLD Bottom up processing sensory analysis that starts at an entry level o Mind interpret what our senses detect o Will detect lines angles etc Top Down processing our previous experiences and encounters that we incorporate into perception o Notice the painting title and the relative meaning of aspects of the painting o Use existing tools to interpret the environment Thresholds effect o Psychophysics physical energy we can detect and its effect on our psychological o Absolute Thresholds the minimum stimulus necessary to detect light sound touch or pressure 50 of the time To determine threshold multiple tests like the beeping test can be used The absolute threshold increases with age as you detect less o Signal detection Detecting the stimulus depends on psychological state experience alertness as well as signal strength Signal detection theory detects when we will detect weak signals Researchers of this kind want to determine why people respond differently to same stimuli Signal detection is important because can weed life and death situations apart Ex airport terminal Experience improves signal detection for specific signal o Subliminal Stimulation Subliminal stimulus below our conscious threshold Because absolute threshold is fifty percent of the time sometimes can detect stimulus lower than threshold An invisible image can prime people for reactions Ex the flash of neg or pos image and the disposition of people that followed Proves that most of our information processing is done unconsciously VISION o Different thresholds Weber s law Sensory Adaptation The difference threshold is the ability of a hiuman to detect the difference between 2 stimuli of the same origin i e light or sound 50 of the time For their difference stimuli to be different two stimuli must differ on a constant proportion not a constant amount o Diminishing sensitivity to an unchanging stimulus Olfactory fatigue o Give us the freedom to focus on novel and informative stimulus o Making us not perceive the world as it is but as it is useful to us Our body tranduces transform light energy into neural signals for our brains to interpret The stimulus input light energy o The pulses of light energy is what strikes our eye o We view a short range of visible light on the electromagnetic spectrum o o Hue the color of the perceivable light Intensity the amount of energy in a light wave determined by amplitude The eye o Light enters the eye through the cornea which protects the eye and bends the light to focus o The light then passes through the pupil which is controlled by the iris o The iris dilates or constricts in response to light intensity or energy o Behind the pupil sits the lens that focuses accommodates the incoming light rays on the fovea and retina o The retina is filled with light detecting cells that convert the light into neural signals and sends to the brain The retina o Rods black and white Located in the periphery and are better used in dim lighting Much more abundant at almost double the amount of cone cells o Cones color Centralized in fovea and some even have specific nerves to send impulses to the brain without the optic nerve Allow to see detail more clearly o The light activates these bipolar cells to produce chemical signals that activate ganglion cells o As the ganglion cells converge they form the optic nerve Carries the info to the thalamus which divides up the information o Where the optic nerve leaves the eye there is a blind spot Processing Visual Information o Feature detection Feature detectors located in the visual perception lobe occipital lobe they allow us to recognize the angles and shapes that make up a specific scene Then sends the signals of recognized features to supercell clusters that analyze and make sense of these complex patterns Ex temporal lob supercell cluster allows us to see faces o Parallel processing The processing of many aspects of a problem simultaneously the brain s natural mode of information processing for many functions including vision Contrasts with the step by step or serial processing of most computers and of conscious problem solving Blindsight when part of the occipital is missing people cannot see a certain region in the field of vision Are able to anticipate a color or direction in this missing area but cannot see it Four aspects of vision are color motion form and depth If cannot see one others can interpret the image The perception of color exists due to the light it reflects it absorbs all other light forms Color is perceived by the theater of our brains and it our brains interpretation Young hemholtz trichromatic theory o Color vision All colors are made up of 3 primary colors The retina in response has 3 types of color cells red green and blue o When red and green are stimulated we see yellow In colorblind people the cells that are responsive to red blue or green are damaged In order to understand why we do not have yellow receptors opponent process theory o We see an afterimage an opponent color or sorts o We analyze light in terms of 3 sets of opponent colors Red green Yellow blue White black and create the image o The combination of varying response to light combine colors HEARING Our audition is reflecting of the range of the human voice Vary adaptable and highly tuned to sound The Stimulus Input Sound Waves o The resulting waves of compressed and expanded air o The strength or amplitude determines the loudness of the stimulus o Frequency the waves s or wavelength Determines the pitch o Measure sounds in decibels o The ear Every 10 decibels is a tenfold increase in intensity The produce is to tranform sound to neural impulse Out ear channels the sound waves to the auditory canal to the eardrum Middle ear transfers eardrums vibrations to the bones pistons and to the cochlea Inner ear the cochlea that transforms sound to neural impulse Fluid filled and lined with hairlike process that response to the vibrating basilar membrane Transfers to auditory nerve to auditory cortex temporal lobe Ringing attunes us to possible damage to the ear o Perceiving loudness o Perceiving pitch The brain can perceive loudness via the number of activated cells People with hearing damage can only hear loud noise because hair cell loses its sensitivity to soft sounds Hemholtz s place theory suggests that we perceive different pitches because different sound waves trigger activity at different places along
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